linux-kernel - Re: [PATCH 31/31] media: au0828 change to check media device unregister progress state

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Date:	Thu, 28 Jan 2016 13:31:23 -0700
From:	Shuah Khan <shuahkh@....samsung.com>
To:	Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc:	tiwai@...e.com, clemens@...isch.de, hans.verkuil@...co.com,
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	alsa-devel@...a-project.org, Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH 31/31] media: au0828 change to check media device
 unregister progress state

On 01/28/2016 10:05 AM, Mauro Carvalho Chehab wrote:
> Em Wed,  6 Jan 2016 13:27:20 -0700
> Shuah Khan <shuahkh@....samsung.com> escreveu:
> 
>> Change au0828_unregister_media_device() to check media
>> device media device unregister is in progress and avoid
>> calling media_device_unregister() and other cleanup done
>> in au0828_unregister_media_device().
>>
>> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
>> ---
>>  drivers/media/usb/au0828/au0828-core.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/usb/au0828/au0828-core.c b/drivers/media/usb/au0828/au0828-core.c
>> index 886fb28..de357a2 100644
>> --- a/drivers/media/usb/au0828/au0828-core.c
>> +++ b/drivers/media/usb/au0828/au0828-core.c
>> @@ -136,7 +136,9 @@ static void au0828_unregister_media_device(struct au0828_dev *dev)
>>  
>>  #ifdef CONFIG_MEDIA_CONTROLLER
>>  	if (dev->media_dev &&
>> -		media_devnode_is_registered(&dev->media_dev->devnode)) {
>> +		media_devnode_is_registered(&dev->media_dev->devnode) &&
>> +		!media_device_is_unregister_in_progress(dev->media_dev)) {
>> +
> 
> A kref would likely work better here.

Hope you saw my response to[PATCH 29/31] on why ensuring
two drivers don't get into unregister is necessary.

Could you please elaborate on kref. Are you saying adding
kref to struct media_device?

thanks,
-- Shuah
> 
>>  		media_device_unregister(dev->media_dev);
>>  		media_device_cleanup(dev->media_dev);
>>  		dev->media_dev = NULL;


-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@....samsung.com | (970) 217-8978